Early detection of invasive tree pathogens using molecular tools

invasive tree disease

Heterobasidion root disease at the base of a tree

Header image credit: "Annosum root disease" by Joseph OBrien, USDA Forest Service, Bugwood.org is licensed under CC BY-NC 3.0



Invasive tree pathogens cause immense damage to natural ecosystems and, in turn, significant economic losses. Minnesota’s natural and urban forests have experienced massive ramifications from the introduction of several exotic pathogens—Dutch elm disease and oak wilt, for example.

A recent, newer threat is Heterobasidion Root Disease (HRD, also called annosum root rot) that has the potential to devastate Minnesota’s pines and other conifers. Many pathogens like HRD spread through windborne spores. Oftentimes windborne pathogens are only detected after being established in an area for some time.

New molecular biosurveillance tools can use DNA technology to help detect forest diseases before they establish. Blanchette’s team is developing such molecular biosurveillance tools for a number of priority invasive pathogens to facilitate early detection of tree diseases across Minnesota.

Research questions

  • What is the best way to trap windborne fungal spores for molecular testing?
  • What are the best sampling methods for invasive Phytophthora species?
  • Where are HRD and other invasive tree diseases detected in Minnesota?

Practical implications

This work will establish a new and effective biosurveillance monitoring program for the early detection of tree diseases in Minnesota. Being able to detect diseases early enables preventative measures to reduce the spread and impact of diseases.


News and media


  • CFANS Research Symposium 2023
  • University of Minnesota Arboretum presentation, 2022
  • Pikes Peak Mycological Society, 2022
  • North Central Forest Pest Workshop, 2022
  • Upper Midwest Invasive Species Conference, 2022

Research team

Robert Blanchette | principal investigator

Benjamin Held | co-investigator

Brett Arenz | co-investigator

Nick Rajtar | MS student

Tessa Kothlow | undergraduate student


Lab or other website



Collaborating organizations

National Plant Diagnostic Network

Minnesota Department of Agriculture

Minnesota Department of Natural Resources

Minnesota Department of Health

USDA Forest Service